This invention relates generally to an electrostatographic printer or copier, and more particularly concerns a method for maintaining motion quality latitude employing a device for cleaning the backside of a photoreceptor belt.
In an electrophotographic application such as xerography, a charge retentive surface (i.e., photoconductor, photoreceptor or imaging surface) is electrostatically charged and exposed to a light pattern of an original image to be reproduced to selectively discharge the surface in accordance therewith. The resulting pattern of charged and discharged areas on that surface form an electrostatic charge pattern (an electrostatic latent image) conforming to the original image. Contacting it with a finely divided, electrostatically attractable powder referred to as xe2x80x9ctonerxe2x80x9d develops the latent image. Toner is held on the image areas by the electrostatic charge on the surface. Thus, a toner image is produced in conformity with a light image of the original being reproduced. The toner image may then be transferred to a substrate (e.g., paper), and the image affixed thereto to form a permanent record of the image to be reproduced. Subsequent to development, excess toner left on the charge retentive surface is cleaned from the surface. This process is well known, and useful for light lens copying from an original, and printing applications from electronically generated or stored originals, where a charged surface may be image-wise discharged in a variety of ways. Ion projection devices where a charge is image-wise deposited on a charge retentive substrate operate similarly.
One type of charge retentive surface typically utilized in the electrostatographic reproduction device is a photoreceptor belt having a base of flexible material. The photoreceptor belt is entrained about a plurality of support rollers so as to form a closed loop path. The photoreceptor belt is driven about the closed loop path to present particular areas of the photoreceptor belt sequentially into association with electrographic process stations to form desired reproductions. Adhered to the backside of the photoreceptor belt is a substrate polycarbonate known as anti-curl back coating. The purpose of this coating is to balance the stresses within the photoreceptor belt and control edge curling. Over time as a photoreceptor belt repeatedly travels around the sharp corners of rollers, backer bars, and other surfaces, the anti-curl back coating begins to wear and flake off in the form of low charged negative particles. As a result, a build up of anti-curl back coating particles occurs on all parts of the module which come in contact with the anti-curl back layer. Additionally, toner particles from the development system, the imaging surface cleaner, and toner airborne in the xerographic module are deposited on the back of the belt. In particular, there is a buildup of anti-curl back coating particles and toner particles on the drive roller, the backer bars, and in the Acoustic Transfer Assist (ATA) device.
Debris particles on the drive roller cause the coefficient of friction of the drive roller to drop appreciably. This buildup of particles on the backside of the photoreceptor belt and drive roller may adversely affect performance of the photoreceptor belt as it is driven about the closed loop path and, ultimately, overall performance of the reproduction apparatus.
A failure mode associated with low drag of the photoreceptor belt. The low drag, which reduces the total contact ratio between the adjoining gear teeth in the drive, substantially decreases the drive stiffness between the drive roller and motor altering the overall drive dynamics of the belt module. The change in drive dynamics renders the existing motor compensation useless, significantly degrading the motion quality latitude of the belt.
Briefly stated, and in accordance with one aspect of the present invention, there is provided an apparatus for removing electrostatically charged particles from a surface.
In accordance with another aspect of the present invention, there is provided an apparatus for controlling velocity variations in a belt wrapped about at least a first driven roller and a support structure, including a drive for driving said first driven roller so as to provide torque to the belt; and a dampener, in contact with said belt, for minimizing variations of the velocity of the belt, said dampener including a power supply for applying an electrical bias to generate a drag force on the belt.